Pneumatic drop hammer



March 31. 1925. 1531, 489 G.'P. MACREADY ET AL PNEUMATIC DROP HAMMER Filed Aug. 13, 1921 2 Sheets-Sheet 1 65 11v VENTOR; v 8 y a A TTORNEY March 31, 1925.

I ca, P. MACREADY ET AL PNEUMATIC DROP HAMMER Filed Aug. 13, 1921 2 Sheets-Sheet 2 L- I U. f 1. LLQE L II ,Li F? 44 w g y i Z0] 55 5o Il I z s g 5 w I 1 l I l 7 I j 70 7/ i 1 r a, INVENTORS ATTORNEY Patented Mar. 31, 1925.

UNITED GEORGE P. "MACREAIDY AND JAMES BOWIE,"'0FPROVIDENGE, RHODEISI'I'AND, 'AS- vSIGrlTO'RS TO "FRANKLIN MACHINE CGMPANY, OF PROVIDENCE, RHODE" ISLAND,

A CORPORATION OF RHDDE ISI'rA-ND.

PNEUMATIC DROE HAMMER.

Application filed. August 13,1921. Serial N 0; 491,900.

To all whom'z'tm-ag concern: 7

Be it known that we, GEORGE Mao- READY and JAMES R. Bowls, citizens of the United -States, and residents of Providence, in the county ofProvidence and State of Rhode Island,have invented certain new and useful Improvements inPneumatic Drop Hammers, of which thefollowing is a specification.

This invention relates to pneumatic vdrop hammers, and more particularly to such drop hammers used inprecision work such as jewelers work and the like. I

Broadly stated, it islan object of the present invention to provide an improved form of drop hammer, in which rebound of the ram shall be effectivelyprevented, so that accurate precision work :may be reliably produced.

More particularly, it is one object to. provide a drop hammerautomatically or manually operable, employing a compressed medium such as air as the actuating agent, and which is controlled by an improved form of control mechanism.

Another feature relates to animproved adjustable exhaust valve, whereby the time lag'of the ram may be predetermined.

Still another feature relates to employing the actuating medium for definitely seating the control valve,-whereby' leakage is effectively prevented, despite wear of the parts.

Another feature relates to sending an impulse of the actuating medium through the exhaust valve thus preparing it for use in exhausting the cylinder and assuring correct operation thereof.

Other objects will appear as the description of the invention progresses.

Like reference characters designate'like parts in the several figures.

Referring to the drawings,

Figure 1 shows a front elevation of the press;

Figure 2 shows-a plan view of a portion of the top of the mechanism with parts broken away;

Figure 3 shows a section taken on the lines 3-3 of Figure 2 with parts'b-roken awav:

Figure 4 .shows a sectionon the lines 44 of Figure 2;

Figure 5 shows a section on the lines-5 5 of Figure 3;

Figure 6 shows a plan view of the exhaust valve;

Figure 7 shows a sectional elevationtaken on.the:l-ines 77 of Figure 6.

10 designates a metal framepreferably of iron -or steel adapted to -be bolted to' a piston or a work tablell .by means of bolts 12. Said frame has laterally J extending webs 13 to impart strength and rigidity to the structure. Theinwardly facing faces Hand 15 of the frame'lO: are substantially naralleland inspaced relation with .each other andthe surfaces thereof. are ground or machined to insure a smooth and even surface.

The upper: portions of the frameslO are secured together by a cross member 16' suitably attached thereto by a plurality of bolts 17 I Slidably mounted along the smooth surfaces 14 and 15 is a ram QO' preferably formed of metal and having a relatively large mass. Said ram 20 is secured to. a plunger rod 21 bymeans of a-clamo 22. Slidablyxmounted on the plunger '21 is an adjustable stop 23, whose. position. maybe changed at will by means ofzainachine screw 24. Resting upon the upperzface of the stop 23 is a spring25 comprising a few coils for taking up the shock, as will be presently set forth. 26 is a trigger attached to the ram and extending from the side thereof for a purpose which will besubsequently described. To the'lower surface of ram 20 may be secured in any well known manner a diepress member (not shown) cooperating with a stationary die press member on the frame or-bench.

The plunger 21 rides through a-stufling box 32 in the cross piece16 as shown in Figure 3 and into a cylinder 30. preferably made of brass or other suitable metal mounted on the upper surface of the cross piece 16. The upper end of. plunger 21 is secured to the piston 31 in any suitable manner; the piston 31' being tightly fitted within the cylinder-3O 11nd being preferably made of a plurality of layers to secure a tight fit. The stufling box 32 is provided with a retaining nut 33 adapted to cooperate with a spanner wrench for tightening the plunger. The upper part 34 of the cylinder may be left open to the atmosphere.

Mounted in a bearing such as along one of the vertical supporting frame members 10 is an axially movable rod 41. Pivotally secured to the upper end of this rod is a bell crank lever 42. A pivot 43 mounted on the frame supports said lever. Pivotally secured to the other end of the bell crank lever 42 is a horizontal rod 44, whose free end is adapted to push against a bell crank lever 45 which is suitably mounted in a horizontal plane on the pivot 46 as shown in Figure 2. Vertical movement of the rod 4-1 caused by the operation of handle 49 results in a horizontal movement of rod 44 and displacement of bell crank lever 45. The end 48 of the bell crank lever 45 intercepts the valve shaft 72 for a purpose which will be more fully described later. The bell crank lever 45 is provided with a retractile spring 47 suitably secured to the pin in the cross-piece 16.

On the frame member 10 opposite that to which rod 41 is secured is a vertical op erating rod 50 axially movable in the trunnion 51 ofthe base and bearing 52 of the cross piece 16 (see Figure 3). The upper extremity of rod 50 extends within a dash pot cylinder 54 and is provided with a tight fitting piston 53. An aperture 55 in an intermediate portion of the said wall of the cylinder 54 permits sluggish movement of the piston 53 in its respective positions. The operating rod 50 is adapted to be retained in a given position by means shown in Figure 4 comprising a spring pressed ball riding in a cylindrical well in the cross piece 16. Two lunar shaped notches in the rod 50 receive the ball ('30 in the predetermined position. An adjustment for the spring is provided by means of a set screw 62 and a suitable lock nut.

A stop member 65 is provided with a handle for conveniently operating the rod 50 when the machine is to be operated manually. Said stop 65 is secured to the rod 50 in any suitable manner, as, for example, by set screw or look nuts. The adjustable stop 66 is slidably mounted on the rod 50 above the ram 20 and may be set in any desired position by means of a set screw shown in Figure 1. By this means the automatic operation of the mechanism is controlled. 67 is a safety stop suitably secured to the rod 50 for preventing extreme operation of the ram 20 in case of failure of stop 66 to be tightly secured or in case-the operator inadvertently permits extreme movement. 7

Slidably mounted 011 the rod 50 is a bracknsenase et 70 having a laterally extending portion terminating in bifurcated ends 71. These ends engage between collars 73 and 77 secured to a valve shaft 72 so that movement of the rod 50 also causes axial movement of the valve. shaft 72. A pair of collars 74, 74 is provided, one on either side of the bracket 70, suitably secured to the shaft 50 by means of pins or the like. The compression springs 75 support the bracket 70 intermediate these collars and are adapted to prevent damage to collars 77 and 7S and other parts of the mechanism if the rod 50 is moved too far. Valve shaft '72 is tightly fitted within a chamber in the valve frame 76, said valve frame being integral with the cross piece 16. The collar 77 by contacting with the lower face of the frame 76 limits the upward movement of valve shaft 72 and similarly a collar 78 suitably secured to the valve shaft 72 by means of a pin 79 limits the downward movement thereof.

An axial hole 80 is drilled for a portion of the length of the shaft, its outer end being sealed by a plug 81 or other suitable means. A groove or channel 82 parallel to the hole 80 is cut in the periphery of valve shaft 72 in such a position and of such length that when the fork 71 is in its extreme downward position, the inlet 83 is connected with the passage 84 leading to the cylinder 30.

The groove 82 is connected with the hole 80 by a passage 85. A passage 86 is provided in the frame 76 in such a position that groove 82 coacts therewith when the valve shaft 72 is in its extreme upper position. A second radial passage 87 in the valve shaft 72 is provided in such a position that the hole 80 is thereby connected with the passage 86 only when the valve shaft 72 is in an intermediate position and for only a relatively short portion of the movement of the valve shaft 72.

A passage 90 interconnected to the passage 86 with an exhaust valve 91 shown in detail in Figures 6 and 7. The exhaust valve 91 is provided with means for adjustably determining the rate of exhaust of compressed medium to the atmosphere so that the action of the weight 20 may be accurately varied. Said exhaust valve 91 comprises a frame or casing 92 forming a hollow chamber open at the top. This chamber is closed by a suitable face plate 93 secured by suitable flathead screws to the casing 92 as shown in Figure 6. In intimate contact with the upper part of the face plate 93 there is provided a relatively flat sliding member 94 provided with an outwardly extending arm having bifurcations for a purpose which will be subsequently set forth. A second relatively flat slide member 95 is secured to the sliding member 94 by means of suitable tea se flat-head screws extending through perforar. tions in the plate-r93 and v:is jheld'in intimate! contact with the lower .face ,ofthe plate A spring 96 positioned within, thecasing 92:: maintains the second sliding member 95- in intimate contact. with, the lower plate 93. Screw-threaded into a lug extending late 11* allythrough the ,casing.,\92, is ,a rod having a thumb nut 97' and a, collar. engaging the forked extension on, the slide 94: andby, r0;

tatingthenut-97 theslide194and slide 95, may

be adjusted in,desirablezposition. The slides 93,, 94 and 95-are provided with suitable pertorations and inone position of the thnmb nut 97 theseperforation-smatch with: each.

other thereby providing passage through the interiorof thecasing92 to atmosphere, and;

in other positions arepartially or-completely.

closed. The. spring 96 compresses theshtle 95 against, the plate 93". so as t-o effectively seal the vcasing. against1leakswhenrthfi valve;

is completely or nearly fully closed The, slides 94 andleamay belockedr n s rab position by means, of thu nb nuts 98; the stems of which enterelongated-slots in the;

201 (see Fig. 2)- The hembsrfil r elhi by a suitable plug an,d;is proyided with a drain channelrclosed by a ,draiu plugt g portion 39 of: valve haf i 2i -SS1 QW i E sure 5 is cutiaway and {the pressure of thea r against the I substantially flat; part of the, valve shaft 72 thuspresses theshaftegarnst the. portion ofthe Jframe76 which seals the. passages 83, S land 86 and provides. a njeffective seal againstescape of the compressed air.

In operation it will first beassurned that the apparatus isshut down. The rain is in its extreme downward position resting upon asuitable die plate not shown The valve shaft 72 is in the downwardposition as shown in Figure 3. The source .of oom; pressed air is now connected to the 11 160113? nism, the valve 36-.being turnedr on,

compressedair traverses thev pipe 35, past-Q sages 83, 82 and Maud enters ,thebottom portion of cylinder thus raising the p s: ton 31, plunger 21: and theram QQ, If the device is to'be operated manually theope a; tor permitsthe ram toberaised; mat the stop, 23 is, immediately below; the cross-piece 16, whereupon the operator raisesthe handle 65, after having released thesame, by aetu; ating handle 49 and thereby, displacing bell crank lever- It, will be, notedth at the compression, spring 25 takes 1 up the, shock and that the adjustable stop 23,; prede nmines the height to which the ram is raised,

ntermediat his Manipu ationh he and 5.:1 -n erd y ew aises t e od 50,] racket- 0: and al haft- 2 nddur ng intermed ate p.9 1he r f heit hve t e ou ce. f mpre sed hi u v conn c ed-by one f e pas ages 2,80,

t xhausta ve ll ithlptlgh it to heht sphere, hus.insuringrropeh operation of the exhaust;valveibeiore introducing ht mpul h m nressedi ah h mthrough. Eurther I, movemento f valve-shatt E 72 upwardly iscoh e t pas age 83 I IQlh, srohv 2 nd hhnnects the pas ase e hyay f grohve 82 o mense we hiisthe over: phrt h rt' he ylihsleh i onhe te l t the atmo phere h d hepeo e... ir Pe mi s he ml; 29 9 ll e eed he r p s predetermi e by e ediuhtme ti t he xhau t; v l e; l de 5 The contactof the ra n 20, with the stations r-pre s. hemhe iccompli hes. he es red o k of tamp ng ut; j welry r he .he The. ig r. 31s br u h hte Cont s i h -cpq ftienit he m hber 5,;anr1- au esd w 5 ar mevemeht il el v r 5 hl l S J t he lve eiti -2Y he hh'y. sthma iclly diseoensstins s ylihhler Q l re h v hs t mhsphere nd gain he metis rhhs a,

h passa e :'8,2 @1E 3:W es u ces p ed. aimed hilte htihel yl aising the Pli$9 l= he am 1 een wises th? it m she he-pheiteh e ih ed u ersandv mhin th re nt l h el i hhh e er 5* s a ain. isr eh i 91 7 the Quee s 1 f. andle 9, he pe at n" et their he n ste ahhhl y s ma y, hwes eSire tswil e no d th h ly, a i gle own a d mhv mehts of he hmfiQ- Permit d-.1 n that as soon as the ram r, cgntact's with the, or e welsh-he e ium g f sh ns-9 effective for restoring the ram to itsupper. PQSitiQnf i c rh h hatieallv re h i s he ent he handle 4:9; is; locked out ot] the way 7 in; 1 any suitable manner Th us the bell. cranlr lever. 45 im control oyerntlie movement of valve ha t; 2 he t p; t i jus ed Q h t, when thetrigger 26 and the ram, 20 reach s p ed te m ne p p tion h l e hanism is h thm t h l hhthhth ins -s d. f; g: l ldby l tlv e mv e e upon drops and acts upon the, work, in the hihem hh ri shsf e the pe ti n en-s st h a ellyep ted: til;-.; he handle hr thredh plate 3fierrht elt h lh pl h'hh-ty; 0t pe hhetiehe hh e 01 f. Whiehe ite suhhy a h h -hmrle e slide 95 is provided with a similar niunber o f penforations such as thgperforations 102 P9i i9 1 e hat: in. I ,P lt iQl s lide 5;.. he pe hrai ns 9am n; he men-t; with the. oorr e ding perforations 10. A at h ad. memehie ht ith as f Q th li e- ,51 m l lshh ens ti um?- able; therewith throughfa recess lll cuti in theplate 93;as clearlyindicatedzin.Figure 7.

The present disclosure is one form in which the invention may be practised, but numerous modifications may be made therein without departing from the spirit of the invention. VVe therefore do not wish to be limited by the present disclosure but instead by the scope of the appended claims.

What we claim is: I

1. In a pneumatic drop hammer, a com pressed air supply pipe, a control valve adapted to alternately admit and release compressed air comprising a perforated body member, an elongated shaft slidable in the perforation thereof, of substantially circular cross section through a portion of its length, the inlet and exhaust passages being disposed on one side of the intermediate portion of said shaft and adapted to cooperate with corresponding passages in the body member, a portion of the-shaft diametrically opposite said shaft passages being cut away to form a chamber between it and the adjacent Wall of the body member and a connection forming a communicating passage between said chamber and said air supply pipe, whereby the compressed air maintains said shaftagainst the portion of the body member having the inlet and exhaust passages, to seal said passages against leakages.

2. In a pneumatic drop hammer and control valve, a source of compressible medium connected to the inlet chamber of said valve for supplying medium to the hammer for raising the hammer, an exhaust chamber for the hammer control by said valve to cause said hammer to drop, said valve being formed with a recess having a conducting passage from said source of compressed medium to said recess for effectively setting said valve.

3. In a pneumatic drop hammer, a controlling valve therefor comprising a perforated body member, a reciprocating shaft slidable through the perforation, a pair of collars fixed to said shaft on one side of said member in spaced relation, an actuated rod substantially parallel to said shaft and in spaced relation therewith, a bracket resiliently supported on said rod having a bifurcated transverse arm partially enclosing said shaft at a point between said collars and a third collar fixed to said shaft on the other side of said member adapted to limit the extent of movement of said shaft, one of said first-named collars being adapted to limit the extent of a different movement of the shaft.

4. In a pneumatic drop hammer, a controlling valve therefor comprising a perforated body member, a reciprocating shaft slidable through the perforation, a pair of collars fixed to said shaft on either side of said member adapted to contact in different positions of the shaft with the respective faces of said member to limit the extent of movement thereof, an actuating rod substantially parallel to said shaft and in spaced relation therewith, and resilient means operatively interconnecting said rod and said shaft.

5. In a pneumatic drop hammer, a controlling valve therefor comprising a shaft for opening and closing the valve parts, a reciprocating rod, a forked member loosely mounted on said rod and engaging said shaft and resilient means operatively interconnecting said rod and forked member.

6. In a die press, controlling means therefor, comprising a reciprocating shaft and a movable stop member to prevent the operation of said controlling means, said stop member comprising a bell crank lever, a retractile spring for maintaining one arm of said lever to intercept the path of movement of said reciprocating shaft, and a manually operated push rod to withdraw said lever from said path.

7. In a pneumatic drop hammer, a controlling valve therefor, a reciprocating rod adapted to operate said valve, and a locking mechanism for said rod comprising a depression in the periphery of the rod, a ball formed to enter the depression, resilient means for retaining said ball in the depression, and means for adjustably varying the tension of said spring. 7

8. In a drop hammer, the combination with a controlling valve for said hammer including a casing and including a member slidable in said casing in one direction, of means for supplying a compressible medium to the valve for lifting the hammer, said slidable member having a recess a conducting passage from said recess communicating with said source of sup-ply whereby movement of the member in a relatively different direction is controlled by said medium.

9. In a drop hammer, the combination with a controlling valve for said hammer including a casing having ports, and includ ing a member slidable in'said casing in one direction, of means for supplying a compressible medium to the valve for lifting the hammer, said slidable member having passages communicating with said ports, at least one of said passages being positioned in the side of said member and a pipe connected to said passage and communicating with said source of supply whereby movement of the member in a relatively different direction is controlled by said medium.

10. In a drop hammer, the combination with a control valve for said hammer including a casing having ports, and including a member slidable in said casing in one direction, of means for supplying an ex pansible medium to the valve for lifting the hammer, said slidable member having passages communicating with said ports, and

lot)

having a recess in a side opposite said passages communicating with said source of supply to retain quality of the medium whereby the member is forced into intimate contact with the face of the casing having said parts therein.

11. In a drop hammer, a ram, a cylinder, a piston slidable Within the cylinder and operatively connected with the ram, a valve casing having ports in one face thereof communicating With said cylinder, a valve member slidable in one direction Within said casing and having passages communicating with certain of said ports at different periods of the movement of said member, and a source of compressible medium for actuating said piston, said valve member having a recess in a side opposite said passages communicating With said source to retain a quantity of the medium whereby the member is forced into intimate contact with the face of the casing having said ports therein.

Signed at Providence in the county of Providence and State of Rhode Island, this eighth day of August, A. D. 1921.

GEO. P. MACREADY. JAMES; R. BOWIE. 

